Rotary tablet presses are core equipment in the pharmaceutical, food, and chemical industries for compressing powdered or granular materials into tablets. With their high efficiency and continuous tablet production capabilities, they are widely used in the production of tablets, effervescent tablets, mints, and other products. Proper operation not only ensures tablet quality but also extends equipment lifespan and mitigates safety risks. The following details the correct operating methods for rotary tablet presses from five aspects: pre-operation preparation, start-up operation, operation monitoring, shutdown maintenance, and safety regulations.
I. Pre-operation Preparation: Laying the Foundation for Safe and Efficient Production
Detailed pre-operation checks and adjustments are crucial for avoiding equipment malfunctions and ensuring tablet quality.
1. Equipment and Material Inspection
- Equipment Appearance and Components: First, observe the overall appearance of the tablet press, confirming that the machine body is not deformed and the connecting bolts are not loose. Open the protective door and check whether the punches and dies on the turntable (upper punch, lower punch, and middle die) are intact—the punches should be free of wear, scratches, or deformation; the middle die hole diameter should be compatible with the material; and the punches and dies should be firmly installed without shaking (if the punches and dies need to be replaced, ensure that the new punch and die number matches the equipment, and tighten them with a special tool after installation).
- Material Preparation: The material to be pressed must meet the requirements of "dry, uniform, and free of impurities" (moisture content is usually controlled between 3% and 8%). If the material has poor flowability, a flow aid (such as micronized silica gel) can be added in advance. Before pouring the material into the hopper, it should be passed through an 80-100 mesh sieve to remove lumps or foreign objects to avoid clogging the punches and dies or damaging the pressure rollers.
- Lubrication and Cleaning: Inspect the equipment's lubrication system to ensure the lubricating oil (usually food-grade or pharmaceutical-grade) level is within the marked range and the oil is clear and free of impurities. Clean components that come into contact with materials, such as the hopper, turntable, and pressure rollers, using purified water or a specialized cleaning agent to ensure no residue or oil contamination remains (for the pharmaceutical industry, GMP cleanliness requirements must be met, and disinfection must be performed after cleaning).
2. Parameter Setting and Adjustment
Set key parameters according to tablet specifications (diameter, thickness, weight):
- Pressure Setting: Adjust the main pressure roller pressure via the control panel (usually 10-50kN). For tablets requiring high hardness (e.g., pill tablets), increase the pressure appropriately; for brittle materials (e.g., effervescent tablets), decrease the pressure to prevent tablet breakage.
- Filling Depth: Adjust the filling depth of the lower punch to control the material filling amount (the greater the filling depth, the heavier the tablet). Initially, set a smaller filling amount, and adjust according to tablet weight differences after trial pressing.
- Speed Setting: The turntable speed must match the material flowability, generally 10-30 rpm. For materials with good flowability, increase the speed appropriately (to increase output); for materials with poor flowability, decrease the speed to ensure full filling.
After adjustment, manually rotate the flywheel 1-2 revolutions to observe whether the die movement is smooth, without jamming or abnormal noise. Once the parameters are confirmed to be correct, prepare to start the machine.
II. Start-up Operation: Standardized Procedures Ensure Safety
1. Start-up and Pressure Testing
- Close the equipment's protective door (rotary tablet presses are equipped with safety interlock devices; the equipment cannot start if the protective door is not closed), connect the main power supply, and turn on the power switch on the control panel. The equipment will enter standby mode.
- Press the "jog" button to slowly rotate the turntable. Observe whether the material enters the die hole evenly and whether the filling is full. If the material filling is insufficient, adjust the opening of the discharge gate below the hopper to control the discharge speed.
- Start the "pressure testing" mode. The equipment will run at low speed (usually 5 rpm) to press 5-10 samples. Remove the samples for inspection: Weigh the tablets using a balance, ensuring the weight difference is within ±5% (the pharmaceutical industry must comply with pharmacopoeia standards); test the tablet hardness using a hardness tester (usually 3-10 kg), and test the disintegration time using a disintegration tester. If the parameters do not meet the standards, readjust the pressure or filling depth until the pressure test is successful.
2. Formal Production:
After successful pressure testing, switch to "Automatic" mode and gradually increase the turntable speed to the set value to begin continuous tablet production. Turn on the material conveying device (such as a vibrating feeder) to ensure the hopper is always at a "half-full" level, preventing uneven filling due to insufficient material. Simultaneously, turn on the dust removal device to remove dust generated during tablet production, maintaining a clean operating environment and minimizing the impact of dust on equipment and operators.
III. Operational Monitoring: Real-time Control of Production Quality
During production, continuous monitoring of equipment operation and tablet quality is necessary to prevent abnormalities from escalating:
- Equipment Monitoring: Closely observe parameters such as pressure, speed, and temperature on the control panel. If the pressure suddenly increases (possibly due to material clumping and clogging the die) or suddenly decreases (possibly due to die damage), immediately press the "Emergency Stop" button. Listen to the equipment's operating sounds; normal operation should be free of sharp noises or metallic clanging sounds. If any abnormalities occur, stop the machine and inspect the die or pressure rollers.
- Quality Monitoring: Sample and check tablet quality every 15-30 minutes: Weight variation must be stable within the set range. If weight fluctuations are excessive, check if the feed gate is blocked or if the filling depth is off-center. Tablet surfaces should be smooth, free of spots and cracks. If "loose tablets" (tablets that are easily broken) occur, increase the pressure or adjust the material moisture content. If "sticking to the die" (material sticking to the die) occurs, clean the die or add an anti-sticking agent (such as magnesium stearate).
IV. Shutdown Maintenance: Key to Extending Equipment Lifespan
After production, shutdown and maintenance must be performed according to standard procedures to prevent residual materials from corroding the equipment or affecting future use:
1. Shutdown Operation
- First, turn off the material conveying device. After the material in the hopper is basically used up, press the "Stop" button to stop the turntable; turn off the dust collector, disconnect the power to the control panel, and finally disconnect the main power supply;
- Open the protective door and clean the residual material from the hopper, turntable, and die. Use a soft brush or compressed air (pressure ≤ 0.4MPa) to remove accumulated material from the die holes to prevent material from hardening and affecting future use.
2. Maintenance and Care
- Punch and Die Maintenance: Remove the punch and die from the turntable, clean it with purified water, and dry it. If it will not be used for a long time, apply rust-preventive oil to the surface of the punch and store it in a special packaging box. Inspect the wear of the punch and die. If the tip of the punch is severely worn or the inner wall of the die is scratched, replace it immediately.
- Equipment Lubrication: Add lubricating oil to the transmission components of the equipment (such as gears and bearings). Refer to the equipment manual for lubrication points to avoid excessive lubrication that could contaminate materials.
- Component Inspection: Inspect the surface of the pressure roller for wear. If the pressure roller has dents or scratches, grind and repair it. Check the sensitivity of the safety interlock device. Ensure the equipment can only be started after the safety door is closed to avoid safety hazards.
V. Safety Regulations: Risk Mitigation Cannot Be Ignored
The rotary tablet press carries mechanical transmission risks during operation. Operators must strictly adhere to safety regulations:
- Wear personal protective equipment (PPE) during operation (e.g., dust masks, non-slip shoes, protective gloves). Wearing rings, bracelets, or loose clothing is strictly prohibited to avoid entanglement in the turntable or transmission components.
- Never open the safety door while the equipment is running. Never touch the die or pressure rollers with your hands. If cleaning or inspection is required, press the "Emergency Stop" button first to ensure the equipment has stopped before proceeding.
- If the die jams (the die cannot move normally), stop the machine immediately. Manually rotate the flywheel to slowly remove the die. Do not forcibly start the equipment to avoid damaging the die or pressure rollers.**
- Regularly train operators to familiarize them with the equipment structure and emergency response procedures to ensure timely and correct handling of any abnormal situations.
Summary
Proper operation of the rotary tablet press requires attention to the entire process of "preparation - startup - monitoring - shutdown - maintenance." It is essential to focus on parameter settings and quality control, as well as safety regulations and equipment maintenance. Only by strictly following the operating guidelines can efficient and stable film production be achieved, while ensuring the long-term reliable operation of the equipment, thus supporting enterprises in reducing production costs and improving product quality.